wicket-extensions/src/java/wicket/extensions/markup/html/repeater/refreshing/Item.java

/*
 * $Id$
 * $Revision$
 * $Date$
 *
 * ====================================================================
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package wicket.extensions.markup.html.repeater.refreshing;

import java.util.Comparator;

import wicket.markup.html.WebMarkupContainer;
import wicket.model.IModel;
import wicket.version.undo.Change;

/**
 * Container that holds components in a AbstractPageableView. One Item
 * represents one entire row of the view. Users should add all containing
 * components to the Item instead of the view, this is accomplished by
 * implementing refreshingView.populateItem(Item item).
 * 
 * @see RefreshingView
 * 
 * @author Igor Vaynberg
 */
public class Item extends WebMarkupContainer
{
	private static final long serialVersionUID = 1L;

	/** relative index of this item */
	private int index;

	/**
	 * @param id
	 *            component id
	 * @param index
	 *            relative index of this item in the pageable view
	 * @param model
	 *            model for this item
	 */
	public Item(final String id, int index, final IModel model)
	{
		super(id, model);
		this.index = index;
	}

	/**
	 * Sets the index of this item
	 * 
	 * @param index
	 *            new index
	 */
	public void setIndex(int index)
	{
		final int oldIndex = this.index;
		addStateChange(new Change()
		{
			private static final long serialVersionUID = 1L;

			public void undo()
			{
				Item.this.index = oldIndex;
			}

			public String toString()
			{
				return "IndexChange[component: " + getPath() + ", index: " + oldIndex + "]";
			}
		});
		this.index = index;
	}

	/**
	 * @return the index assigned to this item
	 */
	public int getIndex()
	{
		return index;
	}


	/**
	 * @return the primary key assigned to this item
	 */
	public String getPrimaryKey()
	{
		return getId();
	}

	/**
	 * Comparator that compares Items by their index property
	 * 
	 * @author Igor Vaynberg (ivaynberg)
	 * 
	 */
	public static class ByIndexComparator implements Comparator
	{
		private static final Comparator instance = new ByIndexComparator();

		/**
		 * @return static instance of the comparator
		 */
		public static final Comparator getInstance()
		{
			return instance;
		}

		/**
		 * @see java.util.Comparator#compare(java.lang.Object, java.lang.Object)
		 */
		public int compare(Object o1, Object o2)
		{
			Item lhs = (Item)o1;
			Item rhs = (Item)o2;
			return lhs.getIndex() - rhs.getIndex();
		}

	};

}